1. Field of the Invention
The present invention generally relates to charged-particle beam exposure methods using charged-particle beam exposure apparatuses and, more particularly, to a charged-particle beam exposure method using a charged-particle beam exposure apparatus equipped with a blanking aperture array plate (hereinafter referred to as a BAA plate) in which a plurality of blanking apertures are arranged two-dimensionally in an array.
2. Description of the Prior Art
Recently, the integration density and function of integrated circuits have been improved and use of such integrated circuits is expected to be a core technique in the progress of computers, communications, and mechanical control so on.
The density of integrated circuits has been increased four times every two or three years. For example, the integration density of DRAMs has been increased to 1M, 4M, 16M, 64M, 256M and 1 G. Such an improvement in the integration density is mainly based on the progress of a fine (i.e., processor) production technique, such as a lithography technique.
A current electron beam exposure apparatus that is a lithography apparatus is capable of performing a fine production at a pitch equal to or less than 0.05 .mu.m with a precision of 0.02 .mu.m or less. However, it is generally said that the throughput of such an electron beam exposure apparatus is low and unsuitable for mass production of LSIs.
However, strictly speaking, the above holds true for electron beam exposure apparatuses of a single-stroke exposure type, such as a point-beam type electron beam exposure apparatus or a variable rectangular beam type electron beam exposure apparatus. Further, in actuality, such electron beam exposure apparatuses have not been sufficiently considered from the physical and technical viewpoints, particularly concerning what causes the low throughput. In other words, the above disadvantage of low throughput is based on the fact that the throughput of the electron beam exposure apparatuses available on the market is actually low.
Recently, a throughput approximately equal to 1 cm.sup.2 /sec has been expected by the proposal of an electron beam exposure apparatus equipped with a block mask (stencil mask) or a BAA plate. The above proposed apparatus is superior to the other lithography apparatuses from many viewpoints, such as precision of formable patterns, positioning and quick turnaround, and reliability. Particularly, an electron beam exposure apparatus equipped with a BAA plate is very attractive because such an apparatus is capable of exposing a random pattern formed on a wafer at high speed, while such a random pattern cannot be efficiently formed by an electron beam exposure apparatus equipped with a block mask.
Nowadays, there has been considerable activity in the development of an electron beam exposure apparatus equipped with a BAA plate. The present invention is intended to provide an improvement in the formation of patterns.